/*
 * Copyright 2020 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.tencent.kuikly.compose.foundation.lazy

import com.tencent.kuikly.compose.foundation.ExperimentalFoundationApi
import com.tencent.kuikly.compose.foundation.lazy.layout.LazyLayoutMeasuredItem
import com.tencent.kuikly.compose.ui.Alignment
//import com.tencent.kuikly.compose.ui.graphics.layer.GraphicsLayer
import com.tencent.kuikly.compose.ui.layout.Placeable
import com.tencent.kuikly.compose.ui.unit.Constraints
import com.tencent.kuikly.compose.ui.unit.IntOffset
import com.tencent.kuikly.compose.ui.unit.LayoutDirection
import com.tencent.kuikly.compose.ui.util.fastForEach
import com.tencent.kuikly.compose.ui.util.fastForEachIndexed

/**
 * Represents one measured item of the lazy list. It can in fact consist of multiple placeables
 * if the user emit multiple layout nodes in the item callback.
 */
internal class LazyListMeasuredItem @ExperimentalFoundationApi constructor(
    override val index: Int,
    private val placeables: List<Placeable>,
    override val isVertical: Boolean,
    private val horizontalAlignment: Alignment.Horizontal?,
    private val verticalAlignment: Alignment.Vertical?,
    private val layoutDirection: LayoutDirection,
    private val reverseLayout: Boolean,
    private val beforeContentPadding: Int,
    private val afterContentPadding: Int,
    /**
     * Extra spacing to be added to [size] aside from the sum of the [placeables] size. It
     * is usually representing the spacing after the item.
     */
    private val spacing: Int,
    /**
     * The offset which shouldn't affect any calculations but needs to be applied for the final
     * value passed into the place() call.
     */
    private val visualOffset: IntOffset,
    override val key: Any,
    override val contentType: Any?,
//    private val animator: LazyLayoutItemAnimator<LazyListMeasuredItem>,
    override val constraints: Constraints
) : LazyListItemInfo, LazyLayoutMeasuredItem {
    override var offset: Int = 0
        private set

    /**
     * Sum of the main axis sizes of all the inner placeables.
     */
    override val size: Int

    /** In lists we only have one lane. */
    override val lane: Int = 0
    /** And each item takes one span. */
    override val span: Int = 1

    /**
     * Sum of the main axis sizes of all the inner placeables and [spacing].
     */
    override val mainAxisSizeWithSpacings: Int

    /**
     * Max of the cross axis sizes of all the inner placeables.
     */
    val crossAxisSize: Int

    /**
     * True when this item is not supposted to react on scroll delta. for example sticky header,
     * or items being animated away out of the bounds are non scrollable.
     */
    override var nonScrollableItem: Boolean = false

    private var mainAxisLayoutSize: Int = Unset
    private var minMainAxisOffset: Int = 0
    private var maxMainAxisOffset: Int = 0

    // optimized for storing x and y offsets for each placeable one by one.
    // array's size == placeables.size * 2, first we store x, then y.
    private val placeableOffsets: IntArray

    init {
        var mainAxisSize = 0
        var maxCrossAxis = 0
        placeables.fastForEach {
            mainAxisSize += if (isVertical) it.height else it.width
            maxCrossAxis = maxOf(maxCrossAxis, if (!isVertical) it.height else it.width)
        }
        size = mainAxisSize
        mainAxisSizeWithSpacings = (size + spacing).coerceAtLeast(0)
        crossAxisSize = maxCrossAxis
        placeableOffsets = IntArray(placeables.size * 2)
    }

    override val placeablesCount: Int get() = placeables.size

    override fun getParentData(index: Int) = placeables[index].parentData

    override fun position(
        mainAxisOffset: Int,
        crossAxisOffset: Int,
        layoutWidth: Int,
        layoutHeight: Int
    ) {
        position(mainAxisOffset, layoutWidth, layoutHeight)
    }

    /**
     * Calculates positions for the inner placeables at [mainAxisOffset] main axis position.
     * If [reverseOrder] is true the inner placeables would be placed in the inverted order.
     */
    fun position(
        mainAxisOffset: Int,
        layoutWidth: Int,
        layoutHeight: Int
    ) {
        this.offset = mainAxisOffset
        mainAxisLayoutSize = if (isVertical) layoutHeight else layoutWidth
        @Suppress("NAME_SHADOWING")
        var mainAxisOffset = mainAxisOffset
        placeables.fastForEachIndexed { index, placeable ->
            val indexInArray = index * 2
            if (isVertical) {
                placeableOffsets[indexInArray] =
                    requireNotNull(horizontalAlignment) {
                        "null horizontalAlignment when isVertical == true"
                    }.align(placeable.width, layoutWidth, layoutDirection)
                placeableOffsets[indexInArray + 1] = mainAxisOffset
                mainAxisOffset += placeable.height
            } else {
                placeableOffsets[indexInArray] = mainAxisOffset
                placeableOffsets[indexInArray + 1] =
                    requireNotNull(verticalAlignment) {
                        "null verticalAlignment when isVertical == false"
                    }.align(placeable.height, layoutHeight)
                mainAxisOffset += placeable.width
            }
        }
        minMainAxisOffset = -beforeContentPadding
        maxMainAxisOffset = mainAxisLayoutSize + afterContentPadding
    }

    /**
     * Update a [mainAxisLayoutSize] when the size did change after last [position] call.
     * Knowing the final size is important for calculating the final position in reverse layout.
     */
    fun updateMainAxisLayoutSize(mainAxisLayoutSize: Int) {
        this.mainAxisLayoutSize = mainAxisLayoutSize
        maxMainAxisOffset = mainAxisLayoutSize + afterContentPadding
    }

    override fun getOffset(index: Int) =
        IntOffset(placeableOffsets[index * 2], placeableOffsets[index * 2 + 1])

    fun applyScrollDelta(delta: Int, updateAnimations: Boolean) {
        if (nonScrollableItem) {
            return
        }
        offset += delta
        repeat(placeableOffsets.size) { index ->
            // placeableOffsets consist of x and y pairs for each placeable.
            // if isVertical is true then the main axis offsets are located at indexes 1, 3, 5 etc.
            if ((isVertical && index % 2 == 1) || (!isVertical && index % 2 == 0)) {
                placeableOffsets[index] += delta
            }
        }
//        if (updateAnimations) {
//            repeat(placeablesCount) { index ->
//                val animation = animator.getAnimation(key, index)
//                if (animation != null) {
//                    animation.rawOffset = animation.rawOffset.copy { mainAxis -> mainAxis + delta }
//                }
//            }
//        }
    }

    fun place(
        scope: Placeable.PlacementScope,
        isLookingAhead: Boolean
    ) = with(scope) {
        require(mainAxisLayoutSize != Unset) { "position() should be called first" }
        repeat(placeablesCount) { index ->
            val placeable = placeables[index]
            val minOffset = minMainAxisOffset - placeable.mainAxisSize
            val maxOffset = maxMainAxisOffset
            var offset = getOffset(index)
//            val animation = animator.getAnimation(key, index)
//            val layer: GraphicsLayer?
//            if (animation != null) {
//                if (isLookingAhead) {
//                    // Skip animation in lookahead pass
//                    animation.lookaheadOffset = offset
//                } else {
//                    val targetOffset = if (animation.lookaheadOffset != NotInitialized) {
//                        animation.lookaheadOffset
//                    } else {
//                        offset
//                    }
//                    val animatedOffset = targetOffset + animation.placementDelta
//                    // cancel the animation if current and target offsets are both out of the bounds
//                    if ((targetOffset.mainAxis <= minOffset &&
//                            animatedOffset.mainAxis <= minOffset) ||
//                        (targetOffset.mainAxis >= maxOffset &&
//                            animatedOffset.mainAxis >= maxOffset)
//                    ) {
//                        animation.cancelPlacementAnimation()
//                    }
//                    offset = animatedOffset
//                }
//                layer = animation.layer
//            } else {
//                layer = null
//            }
            if (reverseLayout) {
                offset = offset.copy { mainAxisOffset ->
                    mainAxisLayoutSize - mainAxisOffset - placeable.mainAxisSize
                }
            }
            offset += visualOffset
//            if (!isLookingAhead) {
//                animation?.finalOffset = offset
//            }
            if (isVertical) {
//                if (layer != null) {
//                    placeable.placeWithLayer(offset, layer)
//                } else {
                    placeable.placeWithLayer(offset)
//                }
            } else {
//                if (layer != null) {
//                    placeable.placeRelativeWithLayer(offset, layer)
//                } else {
                    placeable.placeRelativeWithLayer(offset)
//                }
            }
        }
    }

    private val IntOffset.mainAxis get() = if (isVertical) y else x
    private val Placeable.mainAxisSize get() = if (isVertical) height else width
    private inline fun IntOffset.copy(mainAxisMap: (Int) -> Int): IntOffset =
        IntOffset(if (isVertical) x else mainAxisMap(x), if (isVertical) mainAxisMap(y) else y)
}

private const val Unset = Int.MIN_VALUE
